Besides having some liquid-impermeable barrier film or sheet, hygiene and personal care articles such as diapers, incontinent products and sanitary napkins are often provided with some absorptive capacity for more efficiently containing the liquid or semi-liquid excretions which they are intended to prevent from soiling underwear or other items of clothing.
Even when the article is disposable, malodors caused by volatile components or volatile decomposition products of such excretions can cause discomfort, already during normal wear before the article is disposed.
A related problem arises in the temporary storage of such soiled articles, be they disposable or washable, before their disposal or before laundering, as applicable. Malodors emanating from such stored articles are highly undesirable.
A permeant, contaminant or volatile in the meaning of the present invention is a substance that can exist in the atmosphere at a substantial detectable concentration and can escape from such an article. A large variety of such permeants or volatiles are known.
Usually soiled diapers are stored in a lockable container or resealable garbage bag, which is e.g. placed in the nursery, before transporting them to an outdoor storage vessel. It is widespread to use plastic diaper pails having a tight lid for the temporary storage of the soiled diapers. Said bags or diaper pails reduce the release of the unpleasant odors when sealed. However, the barrier properties of e.g. thermoplastic garbage bags known in the art are limited and are not satisfactory.
In our co-pending application WO 03/025067 entitled “Barrier material having nanosized metal particles” we have disclosed an improved barrier film or sheet material that can e.g. be used to produce improved containers and improved constructive components for articles such as diapers.
While we will hereinafter disclose and exemplify the invention with reference to specific embodiments and applications such as diapers, it is to be understood that this disclosure applies mutatis mutandis to all other comparable articles suffering from similar malodor problems.
Disposable diapers have met with increased commercial acceptance in recent years and many different constructions have been proposed and used. Usually, the moisture absorbing functions are accomplished by a multilayer diaper comprising a liquid pervious top sheet or facing layer, intended to be facing the wearer during use, in the form of a nonwoven material for example a spunbond material. Moreover, disposable diapers often have a liquid acquisition layer between the topsheet and the absorbent body, said liquid acquisition layer having the ability to quickly receive large amounts of liquid, to distribute it and temporarily store it before it is absorbed by the underlying absorbent body. This is important especially in today's thin compressed absorbent bodies often with a high amount of so called superabsorbents, which have a high absorption capacity but in many cases a too low absorption speed in order to be able to absorb the large amount of liquid that can be discharged. The top sheet or facing layer often is made of a porous material and its fibers have less wettability for water than the fibers of the absorbing material, resulting in a tendency for liquid to flow from the facing layer into the absorbing unit. Liquid, which might pass through the absorbing unit during discharge, (when flow is rapid) is held back by an impervious backing sheet or film for sufficient time to permit absorption to take place. However, the outer or backing layer does not prevent volatile substances or odors from permeating through said layer.
The absorbent body can be of any conventional kind. Examples of common absorption materials are cellulosic fluff pulp, tissue layers, highly absorbent polymers (so called superabsorbents), absorbent foam materials, absorbent nonwoven materials and the like. It is known to combine cellulosic fluff pulp with other materials in an absorbent body. It is also common to have absorbent bodies comprising layers of different materials with different properties concerning liquid acquisition capacity, liquid distribution capacity and liquid storage capacity. Conventional absorbent layers or bodies have no odor-controlling properties.
Many of the materials used in the manufacture of the aforementioned sanitary products are fibrous materials. Beside cellulosic fiber materials, materials derived from synthetic or thermoplastic fibers are useful for a wide variety of applications in diapers, feminine hygiene products, incontinence products, towels, medical garments, medical and pharmaceutical products and many others.
It is clear that the problems indicated above with respect to soiled diapers apply to the same extent to other articles, e.g. incontinent products, medical dressings, sanitary napkins or any other article emitting volatile substances.
While some of the malodor problems caused by such soiled hygiene and personal care articles can be overcome by the improvements disclosed in our said co-pending application, it is possible to further improve such articles, in terms of their olfactory properties both in use and in storage after use, by a different approach based on our present invention, as disclosed herein.
In WO 97/33044 the use of cyclodextrin in rigid or semi-rigid cellulosic sheets is disclosed. The cyclodextrin acts as a barrier or a trap for contaminants. The barrier properties of the material disclosed in WO 97/33044 are based on entrapment of the respective permeants in the internal hydrophobic space of the cyclodextrin molecule. The cyclodextrin material is generally used in the form of a compatible, derivatized cyclodextrin. According to WO 97/33044 the preferred cyclodextrin is a derivatized cyclodextrin having at least one substituent group bonded to the cyclodextrin molecule.
Moreover, it is known from WO 97/30122 that the barrier properties of a thermoplastic polymer can be improved by forming a barrier layer with a dispersed compatible cyclodextrin derivative in the polymer.
WO 93/10174 is directed to thermoplastic films containing one or more metal powders selected from aluminium powder, magnesium powder, zinc powder and manganese powder.
The application is directed to a thermoplastic film which is characterized in that the film comprises at least 0.1 wt. %, preferably 0.5 to 6 wt. %, based on the total weight of the mixture of thermoplastic and filler, of at least one metal powder, selected from the group consisting of aluminum powder, magnesium powder, manganese powder and mixtures thereof. According to WO 93/10174 the average particle size of the metal powders is in the range of 5-20 μm.